To avoid that look, I drilled a series of 4 1/8" holes along where the ribbing of the headliner is. Then I used some short sheet metal screws through the loop of the ribbing into the holes. This allowed the headliner to swag between the ribbing just like other areas of the headliner. I used no glue on the sheet metal. Turned out looking pretty good!
Rick Mascari
N64400